Instrument for drawing ellipses or the like



1950 J. w. DIBRELL ETAL 2,493,229

INSTRUMEN-TFOR DRAWING ELLIPSES OR- THE LIKE Filed Aug. 26, 1948 2 Sheets-Sheet l .29 '.c Wi a I t5, 2

C mu IN V EN TORS JAMES w. 0/525 TEI? WHITE A TTOENEYS Jan 3, N56 J, W. D IBRELL ETAL 2,493,229

INSTRUMENT FOR DRAWING ELLIPSES OR THE LIKE Filed Aug. 26, 1948 2 Sheets-Sheet 2 ,0 @Mi'. 5; O

In "HUM "l llllll INIII mmm , w INVENTORS JAMES w 0/52511 PETER WHITE Hu lll w 4 TTOR VEYS Patented Jan. 3, 1950 INSTRUMENT FOR DRAWING ELLIPSES OR THE LIKE James W. Dibrell, Brooklyn, and Peter White, Queens Village, N. Y.; Dorothy Lemmon White, administratrix of said Peter White, deceased,

asslgnor to said Dibrell Application August 26, 1948, Serial No. 46,288

8 Claims. 1

This invention relates to drawing instruments and more particularly to instruments of this kind adapted for the drawing of true ellipses by operations similar to those used for drawing circles with compasses.

A principal object of the invention is to provide an instrument of this character that will facilitate drafting work involving the drawing of ellipses by making it possible to draw any de sired size and angle of view ellipse almost as readily and easily as a circle now can be drawn with an ordinary compass.

A feature of the invention is that it will make possible the drawing of generally perfect ellipses readily and without the use of templates. Thus, draftsmen and industrial design artists will have greater freedom in choosing perspective views because of the elimination of restrictions necessarily imposed by the use of ellipse templates, the standard method. In other words, it will be possible to fit the tools to the work rather than being forced to adapt the work to the available tools.

Another object of the invention is the provision of a mechanically simple device that will be fully effective for the purposes intended and that will be simple to operate and to adjust to render possible the drawing of ellipses of any desired size and angle of view.

Other objects, novel features of the invention will become apparent from the following description and the accompanying drawings, wherein:

Fig. 1 is an elevational view partially sectionalized of a drawing instrument embodying the invention;

Fig. 2 is a side elevational View seen from the right of Fig. 1;

Fig. 3 is a top plan view of the instrument;

Fig. 4 is a fragmentary section taken along the line 4-4 of Fig. 1 and viewed in the direction of the arrows;

Fig. 5 is a longitudinal sectional view taken along the line 55 of Fig. 2 and also viewed in the direction of the arrows;

Fig. 6 is a sectional view taken along line 68 of Fig. 5;

Fig. 7 is an enlarged fragmentary elevational view of structural features included on a smaller scale in Fig. 1;

Fig. 8 is a fragmentary section taken along line 3-8 of Fig. 7 and Fig. 9 is a sectional view taken in the plane of line 55 of Fig. 2 of one of the structural elements of the device.

In general, the invention consists of a mechanical means to generate a cylindroidal surface (which is the limiting form of a convex surface of fixed base as its apex is moved to infinity) having an elliptical perpendicular cross-section,

the major axis length of the elliptical cross-Sec- 5 tion being fixed, with means provided mechanically to adjust continuously as desired the minor axis length of the elliptical perpendicular cross-section and mechanical means to generate simultaneously with the cylindroidal surface a plane which cuts a perpendicular cross-section through the cylindroidal surface as it is generated, together with mechanical linkage to amplify this elliptical cross-section as desired and to project and draw it on a chosen plane surface which also is perpendicular to the axis of the generated cylindroidal surface.

Referring to the drawings, a central shaft or spindle I is provided. The vertical axis of this shaft l0 constitutes a fixed center of rotation about which other operating parts of the device are adapted to be rotated for the purpose of generating and reproducing the ellipse of desired form and angular view as will presently be described.

A knob I! is fixedly secured preferably to the upper end of the shaft Ill and this knob is adapted to be held firmly by the user of the device when the device is operated so as to prevent rotation of said shaft Ill. Portions l2, l3 and M of reduced diameter are provided in the length of the shaft III for purposes presently to be described. The lowermost reduced portion It appears at the lowermost end of the shaft Ill. This reduced portion I4 is provided at its outermost end with a threaded socket l into which a centering pin l6 having a flange l6a is received. This pin l6 has a pointed end I1 which may be positioned at any desired location on a drawing surface 18 such as a sheet of paper or other drawing material on a drawing table IS.

A portion 20 of the shaft lfi intermediate the reduced portions l2 and I3 is flattened and substantially wider in its large dimension than the diameter of the main-body of the shaft I ll, defining the respective shoulders and 22 therewith. A collar-like carrying member 25 is rotatively mounted on the shaft in and rests upon the shoulder 2|. A manipulating rod 26 which threadedly engages the member 25 at 21 extends radially outwardly of the member 25 and preferably at right angles to the axis of shaft l0 and is provided with a manipulating knob 28. A diametrical transversely extending bore or hole 30 is provided in the member 25 and is positioned to lie in the region of the reduced portion I2 f the shaft I0. A guiding rod 3| is slidably guided in the hole 36 of member 25. This guiding rod 3| has a longitudinal slot into which the reduced portion |2 of the shaft ||l fits slidably so that the rod 3| is free to move longitudinally in the bore 36 and in radial directions of the shaft ID at right angles to the axis of the latter. A sleeve 34 is threadedly engaged in an enlarged threaded opening 35 in member concentric with the opening 38. A biasing sprin 36 is carried within the sleeve 34 and surrounds the slotted portion of the rod 3|. One end of the spring 36 engages the face of the member 25 adjacent the threaded opening 35 and its opposite end engages an annular flange 31 attached to the rod 3|. Thus, as seen in Figs. 1 and 5, the spring 36 biases the rod 3| toward the right of said two figures for the purposes presently to be described. A suitable cover 38 is provided for the outer end of the sleeve 34.

A frame-like supporting part 48 is secured to the rod 3| at 4|. The manipulating rod 26 extends through an opening 42 in the frame-like part '40 so that the latter may move freely along the length of said rod 26 in a horizontal direction toward and away from the longitudinal axis of the main shaft |8.

As seen in Figs. 1 and 5. the frame-like part 49 is substantially L-shaped in cross section and the vertical leg of the L has the opening 42 through which the manipulating rod 26 is movable slidably and also has the securing means 4| for the rod 3|.

A collar-like carrying member 45 is positioned on the shaft ID with its upper edge in engagement with the shoulder 22. This member 45 is rotative- 1y secured in this position, for example, by means of the split spring ring 46. This member 45 has a diametrical, transversely extending bore 41 in the region of the reduced portion l3 of the shaft I0. A guiding rod 48 is slidably mounted within the bore 41 for horizontal radial movement relative to the axis of the shaft N). This rod 48 is slotted similarly to rod 3| and biased toward the right as seen in Figs. 1 and 5 by the biasing 58, its longitudinal axis extending in a direction which is substantially parallel to the direction of the longitudinal axis of the shaft Ill. The bar 56 is secured respectively at 51 and 58 to the frame-like part 40 and to the supporting member 53. An extension bar is secured at 6| to the supporting member 53 with its axis projecting parallel with the axis of the shaft l0 and below the cam follower bar 56. Because the bars 56 and 60 are secured respectively to the frame-like part 40 and member 53 and in turn are guided for horizontal movement by the respective guiding rods 3| and 48, the bars 56 and 66 are necessarily movable simultaneously only in radial directions toward and away from the axis of shaft H) but also may be rotated as a unit about said main shaft axis as a center by manipulation of the knob 28 on rod 26. However, they are always maintained in parallelism with the axis of shaft l0 and this disposition may not be changed.

A collar-like carrying member is rotatively 4 mounted on the shaft I0 adjacent the reduced portion l4 being held against removal therefrom by the flange |6a of the pin member l6 and against upward movement relative to the shaft H! by the shoulder 66 and also by engagement of the lowermost end of the bar 60 in a horizontally extending groove 61 provided on the member 65. A horizontally extending bore 68 is pro vided in the member 65. This bore receives a longitudinal slidable guide member 69 which is provided with a longitudinal slot 10 in which the reduced portion M of the main shaft I0 engages slidably.

A scriber or marker support 12 is fixedly attached at 13 to the horizontally movable guide rod 69. A marking member socket 14 provided with a set screw I5 is secured to the member 12 and a marking device such as a pointed lead 16 or other type of scriber is removably supported in the socket 14. This socket 14 has a definite position relative to certain parts, as will be described.

The control mechanism for drawing ellipses comprises a circular ring 80, having substantially toroidal sections, which is supported for rotation about a diametrical axis that is transverse and at right angles to the axis of the shaft |0. As seen in Fig. 6, the outer surface 8| of the ring has substantially semi-circular contour while the irmer surface 82 is substantially straight walled or flattened. The locus of centers generating the semicircular contour is a circle lying in the central plane of the ring 80. This ring 86 is adapted to be supported from the main shaft In so that its with threaded holes 83 and 84. Also, the widened and flattened portion 26 of the shaft I0 is provided with a transversely extending bore 85 having a widened portion 86. The axis of this bore intersects the axis of main shaft I0.

A stub shaft 88 threadedly engages the threaded bore 83 of the ring and extends toward the diametrically opposite bore 84. A flange 88a is provided intermediate the ends of shaft 88 and the latter is threaded at 89 and extends through the bores 85, 86 of the shaft portion 20. An exteriorly knurled internally threaded collar 90 having a portion dimensioned to fit within the widened portion 86 of bore threadedly engages portion 89 of the stub shaft 88. A stub shaft 9| threadedly engaging the threaded bore 84 in the ring 88 rotatively engages in the bore or socket of the knurled collar so that the axes of the two stub shafts 88, 9| are aligned. The adjustable relationship of the stub shaft 88 relative to the ring 80 permits exact positioning of the center of generation of the ring 88 for intersection by the axis of the shaft Ill. The knurling on the "collar 90 permits loosening of the latter on the threaded portion 89 of stub shaft 88 sufficiently to permit an angular adjustment of the central plane of the ring 80, relative to the axis of main shaft l0, and tightening of the collar against :portion 20 of shaft [0 thereafter acts to fix the gular adjusted disposition of the ring 80 on its axis of adjustment, namely, the aligned axes of stub shafts 88 and 9|.

Since it is desirable to permit angular adjustment of the central plane of the ring 89 into near parallelism with the axis of the shaft III, or at least to within approximately 5 of parallelism therewith, clearance recesses 93 are provided in the ring 88 and corresponding clearance recesses 94 are provided in the portion 29 of the shaft Ill. The clearance recesses 93 and 94 are so positioned on the respective parts, namely, ring 89 and portion 29 of shaft I0, as to permit the plane of the ring 80 to be rotated, for example,to the position shown in Figs. 1 and 5 wherein said plane is approximately only 5 out of parallelism with the axis of the shaft I0. Omission of such recesses 93 and 94 would cause engagement of the outer curved surface 8| of the ring 89 with portions 29 of the shaft I9 which would prevent such small relatively angular disposition between the central plane of ring 80 and the axis of shaft I9 and thus preclude the drawing of ellipses having comparatively small axes. However, with the recesses 93, 94 ellipses may be drawn to approximately 2. 5 angle of projection.

A coupling means acting as an amplifier is provided to guide the movement of the marker support I2 in response to movements of the bar 69 as controlled by movement of cam follower bar 55 on the curved surface 8| of ring 88, the said bar 56 being biased into contact with ring 89 by springs 36 and 49. This coupling means includes a slider 95 movable freely but with a close fit on the bar 60 and a second slider 96 movable freely but with a close fit on the main shaft [9 below the collar-like member 45. A pair of spaced projections 91 extend laterally from slider 95 toward the shaft I9 at diametrically opposite sides thereof.

A pair of levers or linkage members 98 are pivoted by pinions 99, one to each of the projections 97. The common axis of the pinions 99 is offset on projections 91 relative to the axis of bar 60 so that its mid-point is intersected exactly by the projection vertically of a point a: on the circle defining the locus of the center of the curved surface 8| of ring 80, this point a: lying in the cross sectional plane of the ring 88 determined by the point y of contact of bar 56 with the curved surface 8! of ring 80. Thus the center point 2 of the common axis of pinions 99 traces out exactly the elliptical projection of the circle defining the locus of centers of the curved surface 8| of ring 89. The levers or linkages 98 are pivoted by pinions IIID to appropriate wings Hi! provided on the marker or scriber support I2. Each lever or linkage member 98 has a longitudinal slot I62.

A pair of headed reference pinions I84 rotatively secure pivot blocks I95 to diametrically opposite points of the slider 96. The mid-point w of the common axis of the two reference pinions I84 is positioned to be intersected by the vertical axis of shaft II]. This point to of intersection is an essential feature in order that the scriber or marker I6 trace out a true ellipse in the use of the instrument as will be described. The concentric heads 16 of pinions I 99 fit slidably in the respective slots I02 of the linkage members or levers 98. Set screws I91 that may be tightened or loosened in threaded holes :98 provided in the respective pivot blocks I95 extend through the respective slots I82 and with the clamp plates 39 facilitate longitudinal adjustment to desired positions of the linkages or levers 98 relative to the common axis of headed reference pinions I94.

6 Calibrations I II! are provided on the surface of levers 98 and serve as references for longitudinal adjustment of these levers 98 to desired positions for purposes of varying the major axes of ellipses to be drawn by the marker IS.

The socket I4 of the scriber support I2 is so positioned that the projection of the point of the scriber or marker I6 supported therein will lie exactly vertically under the center point 1) of the common axis of the pinions I88. Thus the point of the scriber or marker IE will trace out in amplified form depending upon the adjustment of levers 98 relative to reference pinions I98, the true ellipse traced out as described by the point 2 on the common axis of pinions 99.

Operation of the device is as follows. The knurled collar 99 is loosened and the ring 89 is tilted so that its central plane makes a desired angle relative to the axis of the main shaft it. The extent of tilt determines the angle of projection of the ellipse and the minor axis of the ellipse to be traced out by point z. Collar 90 is then tightened to retain the ring 89 in its tilted adjusted position. The levers 98 are then adjusted to desired positions relative to the common axis of reference pinions I94 by first loosening set screws I91 and sliding said levers until the calibrations I I 9 indicate the desired positions of the heads I of reference pinions I99 in slots I92 and then retightening the set screws iii'l. This adjustment determines the desired major axis of the ellipse to be drawn by marker I5.

Point I? at the bottom of main shaft I8 is then positioned on the drawin surface 88 at the desired location and main shaft Iii is held substantially vertical by grasping of the knob II at its upper end. Then, while holding knob iI firmly to prevent rotation of main shaft 59, knob 28 is grasped by the operator's other hand and rotated around the stationary axis of main shaft 58. This rotation acts to rotate the frame-like part 48 around the same axis and also collar-like parts 2! and 45 and the elements attached thereto or operating therein. In such rotation, the biasing action of the springs 39 and 99 acts to maintain the cam follower bar 55 in contact with the curved surface 8| of the tilted ring 89. Bar 99 moves in unison with cam bar 56.

Since the curved surface an is circular, the contact point 1 between cam follower bar 56 and this surface 8| as the bar is moved around the ring 89 is such that the vertical projection of this contact point traces out a locus of points always equidistant from and everywhere perpene dicularly larger by the radius of the generating circle of the curved surface SI than the ellipse formed by a perpendicular projection of the circle defining the locus of the centers of generation of circular surface 8i. However, since the point z of the common axis of pinions as is offset as described to underlie the vertical projection of points a: on the said generating circle, a true ellipse also is traced out by the center point z of the common axis of pinions 99 of linkages or levers 98. This ellipse is exactly the vertical projection of the circle defining the locus of centers of surface 8| of ring 89. Since the center point w of the common axis of the reference pinions I94 intersects the vertical axis of shaft I9, and since the point of marker 78 is vertically aligned with the center point 1) of the common axis of the pinions I99, the marker point moves in unison with point 2; and traces out an exactly similar ellipse of amplified magnitude, however, relative to that traced out by the center point e and draws the desired ellipse on the drawing surface IS. The simplicity of operation is obvious.

The recesses 93, 94 permit angular adjustment of the center plane of ring 80 to within approximately 5 of parallelism with the axis of shaft I and thus permits tracing out, if desired, of

extremely narrow ellipses, that is, ellipses drawn to approximately a angle of projection.

The horizontally disposed guide rods 3| and 48 to which the cam follower bar supporting parts 40 and 4| are secured under biasing action of springs 36 and 49 limit movement of the said bar 56 and also the bar 60 to horizontal to and fro motions toward and away from the aXis of the main shaft l0 so that when the knob 28 is rotated around said axis as a center these bars 56 and 60 describe or generate cylindroidal surfaces having a perpendicular elliptical cross section which is the vertical projection of the circle defining the locus of centers of the curved surface 8! of the tilted ring 80 and the point 2 then traces out this elliptical cross section while point 12 and the point of scriber i5 trace out the same elliptical cross section amplified, however, by linkages or levers 98 to an extent determined by the setting of the linkages or levers relative to the heads I06 of the reference pinions IN, the point '6 drawing this as the desired ellipse on the drawing surface [8.

The structure described thus provides a comparatively simple arrangement for quickly drawing true ellipses of desired major and minor axes and narrow or large angles of projection at desired points on a drawing surface, eliminating the need for templates and enabling a user to fit the instrument to the work, rather than requiring the fitting of the work to the instrument.

While a specific embodiment of the invention has been disclosed, variations in structural detail within the scope of the claims are possible and are contemplated. There is no intention, therefore, of limitation to the exact details shown and described.

What is claimed is:

1. A drawing instrument of the character described comprising a main shaft, a ring having a circular outer surface and whose central plane is angularly adjustable relative to the axis of said shaft, a cam follower rod movable over the outer surface of said ring, supporting members rotatably carried on said main shaft, guide rods movable in said supporting members radially of said main shaft, members fixed to said guide rods, said cam follower rod being secured to said last-named members with its axis in parallelism with said main shaft axis, spring-biasing means for maintaining surface contact between said follower rod and the outer surface of said ring, a bar extending in parallelism with said cam follower rod and secured to one of said two lastnamed members, a marker support, supporting means rotatively carried on said main shaft and having a slot therein engaged by an end of said bar, a guide rod movable in said last-named supporting means radially of said main shaft and secured to said marker support, a marker carried by said marker support, a slider member movable over said bar, a slider member movable over said main shaft, linkage levers pivotally secured at opposite ends respectively to said first-named slider member and to said marker support and having longitudinally extending slots, reference pivots secured to said second-named slider member and slidable in said slots of said linkage levers, and adjusting means to fix the locations of said iii reference pivots at desired positions in said slots.

2. In a device as per claim 1 in which the pivotal support of said linkage levers to said firstnamed slider member is on a horizontal axis that is intersected at its midpoint by a vertical projection of the locus of centers generating the curved surface of the ring in a plane perpendicular to the point of contact of the cam follower rod with the circular surface of the ring, and in which the pivotal support of said linkage levers to said marker support is on a horizontal axis that is intersected at its midpoint by a vertical upward projection of the point of the marker, and in which the reference pivots are on a common horizontal axis that is intersected at its midpoint by the main shaft axis.

3. A device as per claim 1 in which said springbiasing means are mounted on said first-named guide rods.

4. A device as per claim 1 including manipulating means secured to one of said first-named supporting members for moving said cam follower rod over the outer surface of said ring, said manipulating means including an arm secured to said one of said supporting members and slidable in one of the members fixed to one of said guide rods.

5. A drawing instrument of the character described comprising a main shaft, a ring having circular curved contour in its outer surface, adjustable means for securing said ring to said shaft for angular adjustment of the central plane of the ring about an axis transverse to the axis of the shaft and with the center of the ring intersecting the shaft axis. said shaft and said ring having recesses disposed to permit said plane to be adjusted to make relatively small angles between it and the shaft axis, tightening means for fixing said ring in adjusted positions, a cam follower bar movable over the curved outer surface of said ring, supporting means for maintaining the axis of said bar in parallelism with the axis of said main shaft, carrying means for said supporting means rotatable about said main shaft, a rod attached to said supporting means with its axis parallel with that of said bar, a slider movable on said rod, levers, pivots securing said slider to said levers, the mid-point of the pivot axes being disposed to be intersected by the vertical projection of the locus of centers generating the circular surface of the ring in a plane at right angles to the central plane of the ring and including the contact point between the ring surface and the cam follower bar, a second slider movable over said main shaft, reference pivots secured to said second slider and having a, common axis intersected at its mid-point by the main shaft axis, said reference pivots engaging in slots in said levers, a marker, a marker support, carrying means for said marker support rotatably mounted on said shaft, said support being movable in radial directions on said carrying means toward and away from said main shaft axis, said rod slidably engaging a portion of said lastnamed carrying means and pivots having a common horizontally disposed axis securing said levers to said marker support, said last-named common axis being bisected by the vertical projection of the point of the marker carried by said marker support.

6. A drawing instrument of the character described comprising a main shaft, a ring, a stub shaft secured to said ring and extending in a diametrical direction thereof into an opening provided in said main shaft, a second stub shaft adjustably secured to said ring at a diametrically opposite point thereof from said first-named stub shaft with its axis alined with the axis of the first stub shaft, said first-named stub shaft having a threaded portion, a coupling sleeve having a threaded portion to threadedly engage said firstnamed threaded portion and also having a socket alined with the alined axes of the two stub shafts to receive said second stub shaft, said sleeve being capable of being tightened on the threaded portion of said first-named stub shaft against a surface of said main shaft to maintain said ring in adjusted angular positions on said main shaft, said opening in said main shaft being positioned so that the alined axes of the two stub shafts intersect the axis of said main shaft, a follower movable over the surface of said ring, a marker, a marker support and coupling means connecting said marker with said follower.

7. A device as per claim 6 in which said coupling means includes amplifier levers pivotally secured to said marker and to a portion of said follower.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 324,395 Marichal Aug. 18, 1885 1,168,546 Odin Jan. 18, 1916 FOREIGN PATENTS Number Country Date 291,324 Great Britain May 31, 1928 436,830 Great Britain Oct. 18, 1935 603,712 Germany Oct. 6, 1934 

